Pressure operated electric circuit controller



Dec. 1, 1931. E. J. DASHNER PRESSURE OPERATED ELECTRIC CIRCUITCONTROLLER Filed Jan. 4, 1929 Patented Dec. 1, 1931 UNITED STATES PATENTOFFICE EMERY J. DASH'NER, OF BELMONT, MASSACHUSETTS, ASSIGNOR TO J. E.MCALMAN, OF

WINCHESTER, MASSACHUSETTS PRESSURE OPERATED ELECTRIC CIRCUIT CONTROLLERApplication filed January 4, 1929. Serial No. 330,312.

This invention relates to systems of electric circuit control in whichthe circuit is opened and closed by a main switch operated by a relaydevice, which in turn is governed by a primary switch. Its object inthis regard is to provide in a primar switch for the purpose indicated,adjusta le pressure operated means for causing the relay con trollingcircuits to be opened and closed at definitely established limits of apressure or temperature ditferential. That is, my ob ect is to enablethe differential between the pressures or temperatures at which the mainswitch is respectively opened and closed to be set, adjusted andmaintained at accurate points in a range of temperatures or pressures.

In another phase the invention relates to features of construction of apressure operated switch with the object of improving the same inparticulars which are described in the following specification.

These and other objects and the princi les of which the inventionconsists can be est set forth in connection with a detailed descriptionof one embodiment of the invention Fig. 5 is a cross section on line 5-5of Fig. 3;

Fig. 6 is a cross section similar to Fig. 5, but showing a dilferentform of switch con; taining certain features of the invention which areclaimed herein;

Fig. 7 is a wiring diagram of a circuit conwhich may be a heating coilor other heating unit, an electric motor, a set of electric lights,

or any other contrivance operated by electric current undercircumstances of use which require the current flow to be turned on andoil from time to time. 1) represents genericalw ly a relay switchdevice, which may be an apparatus of any character adapted to close andopen the circuit in which the load is included, under control ofdifferent primary electric circuits, current flow through one of 55which causes the relay switch to be closed, and flow through the otherof which causes the relay switch'to be opened. 1 is the controller inwhich particularly the present invention is embodied, the same beingconnected with the relay device by three wires, herein designated as C,H and L, respectively. C is the center wire of the three and is inconnection with the source of current, whatever that may be, whichdelivers current to the load circuit. When thecircuit is completedbetween wires C and L by the controller 1, the

relay is operated to complete the circuit through the load, and whenconnection be tween C and L is broken, and a connection is made from Cto H, the relay switch in the circuit of the load is opened. That is,these results occur when the conducting elements of the circuit and ofthe controller are'ar ranged and connected as shown in the presentopposite to those just described will occur.

; construction, the back may be made as a casting having a peripheralflange 9 rabbeted at its edge to receive the side walls 3; such sidewalls may be made of a section of seamless tubing of suitable diameterand length, and the cover may be made of sheet metal with '1 its flange4a drawn or spun at its circum- The dial 7 is supported by beingference. fastened to two, or permissi y a eater number of, lugs 10 whichare partially severed from the side walls by cuts extending inwardlyfrom the forward edge thereof, and bent toward the interior of the case.

A base plate-11 'of insulating material is mounted on the back of thecase, in an adjustable manner presently described, and on this plate arefastened bars 12 and 13 of conductmg material and a pivot 14 of a lever15, which likewise is made of conducting material. The bar 12 isconnected by a conductor 16 with a binding post 17 to which also thewire H is connected. Said bar contains a socket 18 in which is a slidingcontact piece 19 under pressure of a spring, shown in Fig. 5, whichtends to ex 1 it from the socket to the limit permitted a stop 20 on thestem of the.contact piece. The bar 13 is connected by an electricalconductor 21 with the binding post 22 to which the wire L is connected.In

this bar is a stationary contact 23 which re jects toward the contact 19and is secure by a set screw 24 in a manner permitting it to be adjusted endwise so that it will protrude more or less. The lever 15 isconnected by means of a conductor 25 with the binding post 26 to whichthe wire G is likewise connected. This lever extends between thecontacts 19 and 28 and has opposite faces adapted to en distance betweensuch faces, the distance to which the sliding contact 19 projects, andthe range of adjustment of the contact 23 have such values that thelever may be caused to leave either contact when coming into engagementwith the other, but theexcess of space between the contacts may bediminished to the vanishing point.

A curved spring tube 27 of flattened cross section, closed at one endand open at its other end, is secured to a socket 28 with its open end.entering the socket and in communication with the passage 29 therein.Such socket passes through the side wall of the casing and is providedwith flanges which are secured thereto by screws. This 5 ring tubecorresponds to the familiar Bour on spring of a pressure or vacuumgauge, and the socket to the usual socket of such gau es. To the socketis connected a pipe 30 which conducts fluid, whether liquid, gas orvapor, from any source whatsoever,

The spring tube is desi ed to shift the switch lever 15 when flexe byvariations in its contained fluid pressure,-and to that end a lostmotion connection is provided consistin of a bar 31 carried by the sprintube, and a oop or frame 32, through whic said bar extends; the loop orframe being secured on the end of'a post 33 which in turn is rigidlysecured to an arm 34 projecting forwardly from the lever 15. By thismeans, distortion of the spring tube caused by increasing-pres-- toreturn into engagement with the fixed contact, being actuated tothat endby a spring 35, and by gravity also when the controller is placed 1n anupright position. The spring 35 is here shown as made of a length ofspring wire coiled about a stud 36, which holds it in position, andpressing at one end on the switch lever at a point remote from the pivotof the latter, while its other end bears on the hub portion of the leverwhich serves as an abutment. 7

The bar 31 previously mentioned extends approximately parallel to aportion of the spring tube 27. It is connected to the spring tube byarms 37 and 38 at its opposite ends which are soldered or otherwisesuitably fastened to the spring tube. The arms 37 and 38 ma beconveniently made from the opposite en s of a. single, suitably bent,piece of wire, the central part of which is passed through the tubularbar 31 which is a sleeve or sec tion of tubing made of rubber or othersuitable insulating material. However, an equivalent structure may beconstructed other wise as to its details. Important features, however,are that the bar has substantial length, is spaced away from the s ringtube toward the center about which t e tube is curved, and hassubstantially less width than the space enclosed by the loop or frame82, as well as that it extends generally arallel to that part of thespring tube besi e which it lies. These characteristics permit lostmotion between the spring tube and the switch arm and likewise permit anadjustment whereby the switch will be operated on a greater or lesspressure diiferential.

To permit of the adjustment last referred 39 which passes through a holein the back of the case and has a flange 4O bearing against the innersurface of the back wall, to which the base plate 11 is secured. An arm41 on the outside of the back wall is secured to the protruding end ofthe pivot, the latter preferably having a non-circular outline and thearm 41 having a hub with a hole complemental thereto, which is heldthereon by the overlying head of a screw 42 threaded into the pivotstud. The adjusting arm 41 has a -widened slotted part 43 throu h whichrotrudes a stud 44, mounted on t e back the of the loop 32 in pathsapproximately conb case and carrying a clamp nut 45. The arm also has ahandle or finger piece 46 extending beyond the circumference of thecase. By means of this handle the entire switch (comprising the baseplate, contacts and switch lever, with their electrical connections) maybe rotated as a unit about the axis of the case within the limits of theslot in the ad'usting arm. As the s ring tube 27 is curve about a centernear t eaxis of the case, these ad justments shift the inner and outermembersv centric with the tube. Thebar 31, however,

i is not concentric with the axis of adjustment but is so inclined that,when the switch is in one extreme position, that illustrated in Figs. 1,2, 3 and 5, the lost motion between the bar and the upper member of theframe is a maximum, while in the other extreme adjustment, shown in Fig.4, the lost motion is 8.

a minimum. -In the tter position, moreover, the frame is brought nearerto the end pointer or index 8, and for that purpose a pair of arms orjaws 47 are connected to the 4 index and receive between them a rod 01finger 48 which is mounted on the switch base 11. As a convenient detailof construction,

the 'aws or arms 47 are made as integral proshaped bar 49, the ends ofwhich are parallel to one another and are apertured and placed upon afixed stud 50 which is mounted in a lug 51 on the socket 28, and servesas a pivot. The index 8 is secured to the forward end or leg of thisU-shaped bar. This construction enables the U-sha ed bar and the jaws 47to be formed out o a single blank of sheet metal.

The foregoing description is given with reference to the normal orrelaxed condition of the spring tube, which is the condition shown inthe drawings. The action of a Bourdon spring, of which the tube 27 isone example, when distorted by increasing internal pressure, is toapproach a straight line, and that part of the tube to which the bar 31is attached moves in a direction conforming in 32 is constrained by thepivot 14 to move.

The first part of this movement has no effect on the switch, when theadjustment is such that any space is left between bar 31 and the top ofloop 32, but after the bar 31 has crossed-the space provided for lostmotion it engages the upper member of the loop and withdraws the switchlever from contact 23, shortly afterward bringin it into contact withthe other contact 19. y means of the adjusting arm 41, the preliminary10st motion may be varied between zero and any desired maximum; while byadjustment of the fixed contact-23 the movement of the switch leverafter leaving one contact and before reaching the other may be made asgreat or little as desired, some lost motion being necessaiiy in allcases, however.

11 the foregoing description it has been assumed that the shifting ofthe switch occurs between atmospheric pressure and pressures higher thanatmospheric. However, the same principles are applicable to situationsin which the action is controlled y vacuum conditions. The same Bourdonspring, or other pressure responsive a ent, which is displaceable in onedirection mm a condition of rest by internal pressures greater thanatmospheric, is displaceable in the opposite direction by atmosphericpressure when a artial vacuum is created in its interior. A are reversalof the contacts 19 and 23 is sufiicient to make the controllerhereinbefore described operate under vacuum conditions; and indeed itmay be so of the spring tube whlch has the greatest amplitude ofmovement when distorted by pressure. I

operated even without such reversal by ad justment or arrangement of theparts in such fashion that the switch lever engages the contact 1 9and'is se arated from the contact 23 when the Bour on spring is in thenormal position of rest. 9

-A somewhat different construction organized for vacuum operation isshown in Fig.

6. In this case the normally stationary contact 23a is carried by a bar52 projecting from the base 11a, and the circuit is closed and opened bymovement of a contact 1902 into and out of engagement with the contact23.

The movable contact 19a is virtually a re-v versed duplicate of thecontact 19 except that I y in place of the stop collar 20, a frame 53 issecured to its protruding shank, and its gulde 1s ofiset so that it maybe embraced y such frame. The to bar of the frame lies beneath theoperating bar 31 (when the controller'is in t e position shown in thedrawlugs) so th t contraction of the Bourdon spring by vacuum causes themovable contact to be Withdrawn from the fixed contact. In

other respects, including the capacity for adj ustment of the switch andthe effects obtainable thereby, this form of controller is essentiallylike that previously described.

Inasmuch as the controller connected in gages either contact, currentflows only long enough-to actuate the relay so as to open or close themain switch, as the case may be, and the relay may be operated b acurrent of small magnitude, and after eing operated breaks the circuit.That is, various relay devices known to the art do so, and my controlleris desi ned to cooperate with such relay devices. hen used in suchconditions there is no sparking or tendency to create an electric arewhen the switch arm is withdrawn from either contact. The form of switchshown in Fig. 6, however, is adapted to carry a heavy currentcontinuously and for that purpose its contacts are large and massive,having plane faces which are perpendicular to the line in which thecontact 19a is constrained by its guide to move. Thus the contactmembers have a multitude of points in contact when they are broughttogether, through which current may flow, and such points aresimultaneously and equally separated when the movable contact iswithdrawn from the other; wherefore the heating efiect at the contactarea is small even though a large current is passed, and sparkin uponseparation is largely prevented.

ontrollers embodying the principles of this invention are usable in manysituations for a great variety of purposes, whether for the purpose ofgenerating heat, mechanical power, or light. The actuating force in thecontroller here illustrated is pressure, which may be created in a fluidby heat or by mechanical power. If control by temperature differentialis desired, the pipe or tube 30 may be connected with a closed bulb orthe like containing the fluid, and if the limiting temperatures are bothlow, the fluid used may be a volatile fluid having a low boiling point.Or the pressure may be transmitted by expansion or contraction, withoutvaporization, oi a liquid; or by like actions of a fixed gas.

The Bourdon s ring here shown is merely one illustration 0 a pressureresponsive element. Other pressure responsive devices are known and maybe applied to the purposes of the invention as equivalents of thespecific one shown. Since pressure developed by heat is a function ofthe temperature, t e pressure responsive element when used undertemperature control. is likewise a temperature responsive element, forwhich various other equivalent temperature responsive devices ofspecifically different construction may be used within the scope of theinvention. Therefore the term temperature responsive element is used ina generic sense to include all equivalent devices which are distorted bytemperature diiferences, whether by direct effect on the element orindirectly through conversion into pressure differences, or are capableof being so distorted.

What I claim and desire to secure by Letters Patent is:

1. A circuit controller comprising a curved temperature responsiveelement, an electric switch mounted for angular adjustment about-an axisnearly coaxial with the curvature of said element, a bar carried by saidelement and extending generally len thwise thereof near the end thereofwhich as the greatest movement when distorted in response to temperaturechanges, a frame connected to the circuit closin and opening member ofsaid switch having a portion crossin said bar adapted to be engaged andmoved y the latter when the temperature responsive element is distorted.

2. A circuit controller comprising a curved temperature res onsiveelement, an electric switch mounte for angular adjustment about an axisnear the center of curvature of said element, a bar carried by saidelement near the end thereof which has the greatest movement whendistorted in response to temperature changes, a frame connected to thecircuit closing and opening member of said switch having a portioncrossing said bar adapted to be engaged and moved by the latter when thetern )erature responsive element is distorted, sai bar occupying aposition inclined to the path in which the said frame portion is movedby adjustment of the switch, whereby such adjustment causes a distanceof varying width to exist between the bar and frame ermitting greater orless movement of t c temperature responsive element to occur before theswitch member is shifted.

3. In a controller of the character described, an angularly adjustableswitch, an

index pivoted independently of the switch, and a rejection on saidswitch engaging said in ex at one side of its pivot and arranged to movethe index angularly when the switch is so adjusted.

4. In a controller of the character described, an adjustable movableswitch, a bar having upturned parallel apertured ends, a stationar ivotoccupying the apertures therein and aliout which the bar isoscillatable, saidbar having also arms or jaws extendin side by sidefrom its opposite edges, an index secured to one of the upturned ends ofthe bar and a projection from the switch entering between said jawsadapted to move the same and the index about said pivot when the switchis adjusted.

5. A circuit controller comprising a casing, a switch base mounted insaid casing with provision for rotative adjusted movement, separatedelectrical contacts and a pivoted switch lever between them, mounted onsaid base and insulated from one another, separate conductors leadinrespectively from said contacts and switch lever a and ads ted to be searately connected with the con uctors of a t rec-wire electrical stern,a curyed temperature responsive e ement mounted in said casesubstantially coaxial with the switch base, being secured at one end andfree at the other, a bar carried by said element near the free end ofsaid element and extending generally longitudinally thereof; and a frameconnected to said switch lever and having a member extending across saidbar and the path of movement thereof.

' In testimonyv whereof I have afiixed my signature. EMERY J. DASHNER.

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